I suppose they are taking the Cemetery by eminent domain and basically do as they please. Some years ago here in Texas they relocated a cemetery due to a new lake going in but not for a highway.
I would contact anyone and everyone if possible including your state representatives and the Governor's office.
Here the land for a cemetery is bought and a deed received, the plot is on a map or survey is given with meets and bounds just like your house.
Good luck and keep us updated.
Randy
Land is so valuable in San Francisco that every grave was moved out of town and it's illegal to establish a new cemetery there, so municipalities do move burials if there is a reason they feel is important.
Rich, the company I work for doesn't own cemeteries in New York because we own funeral homes and it's illegal there to own both, so I'm not familiar with the NY statues but as far as I know there are no leases anywhere in the US. When someone purchases an interment right it's forever. New York is a weird place, though, so you may be correct!
Some European countries lease their cemetery spaces for 25 years at a time.
I really like Neil's idea. Don't fight it head-on. Instead, make it so expensive for them that they abandon the idea on their own. Also, every state has some sort of funeral or cemetery oversight agency. Be sure to contact that agency with your concerns.
